Fragments of plastic products have invaded lakes and artificial water basins on a global scale. Shedding light on the extent of contamination and its causes is a new international study led by the University of Milano-Bicocca, involving 79 researchers from the Global Lake Ecological Observatory Network (GLEON), which is engaged in freshwater environment scientific research on a global level. Representative water samples from various environmental conditions were collected from 38 lakes in 23 countries spread across all continents except Antarctica.

The study has been published under the title "Plastic debris in lakes and reservoirs" in the journal "Nature" (DOI: 10.1038/s41586-023-06168-4).

The Aquatic Ecology Sector of the Institute of Earth Sciences of SUPSI participated in the research activities by collecting samples from Lake Lugano. The presence of plastic has also been detected in even the most remote lakes; however, larger lakes and those with more urbanized catchment areas have been found to be the most affected. Notable among these are Lake Maggiore and Lake Lugano, Lake Tahoe (United States), and Lough Neagh (Northern Ireland), which are crucial for water supply and local economies.

Plastic pollution can have detrimental effects not only on human economies but also on aquatic organisms and ecosystem functioning. "For instance," explains Camilla Capelli from the Aquatic Ecology Sector of SUPSI, "microplastics can cause toxicity and disrupt natural material and energy flows." Furthermore, the study's findings offer a new perspective on the role of freshwater bodies in the plastic waste cycle.

"Freshwater continental bodies have been predominantly described as transporters of microplastics from terrestrial environments, where they are produced, to the oceans," explains Federica Rotta, a doctoral student at the Institute of Earth Sciences of SUPSI. "However, this study debunks that notion, showing how lakes can also accumulate concentrations of microplastics that could be environmentally harmful."

"Nevertheless, the high contamination of Lake Lugano and Lake Maggiore shouldn't cause alarm," adds Fabio Lepori, head of the Aquatic Ecology Sector at SUPSI. "Rather, it should serve as a result that prompts greater awareness of the human impact on our waters and the search for solutions to safeguard ecosystems and biodiversity."

The study was coordinated by researcher Veronica Nava, under the supervision of Professor Barbara Leoni, coordinator of the Ecology and Water Management research group at the Department of Environmental and Earth Sciences of the University of Milano-Bicocca. "The results," concludes project coordinator Veronica Nava from the Department of Environmental and Earth Sciences at the University of Milano-Bicocca, "demonstrate the global extent of plastic pollution: no lake, not even those farthest from anthropogenic activities, can truly be considered uncontaminated. This should compel us to reevaluate pollution reduction strategies and waste management processes."

In some lakes, the detected plastic concentrations have been higher than those found in oceanic plastic islands, the so-called garbage patches. The study shows how lakes and water basins, especially larger ones, can be regarded as "sentinels of pollution," as they act as collectors and integrators of various plastic sources from the watershed and atmosphere.

Contact Information:
Institute of Earth Sciences
Department of Environment Constructions
and Design
+41 58 666 62 00
limnologia@supsi.ch